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<br />, <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />i I <br />I <br />I <br />I <br /> <br />approximately 3,190 cfs leaves the main channel of South Boulder Creek and discharges <br />onto the southern portion (South Overflow) of the Flatiron Property, between Cross <br />Sections 30060 and 30080, see Figure 5 for delineation of these flows and the resulting <br />100-year floodplain. <br /> <br />In addition, the main channel of South Boulder Creek will overflow (Main Channel <br />Overflow) to the west at US Highway 36 running parallel with U.S. 36 on the northern <br />edge of the Flatiron Property. The "no berm with 200-foot channel" HEC-2 analysis <br />indicates approximately 490 cfs will discharge to the west along U.S. 36. The spill <br />discharge from the South Overflow (those floodwaters which enter the Flatiron Property <br />at the southeast comer of the property and are intercepted by the interceptor channel) of <br />3,190 cfs meets the U.S. 36 spill of 490 cfs, and the resulting backwater results in a spill <br />of about 530 cfs through the opening at the RTD Park-N-Ride facility. The overflows <br />(both South Overflow and Main Channel Overflow) continue west and northward and <br />exit at a low point in U.S. 36 discharging an additional 3,150 cfs towards Apache Road, <br />at Cross Section 90. The spill discharge estimates and the 100-year floodplain for <br />Condition 1, in the vicinity of the Flatiron Property, is shown on Figure 5. Under the <br />"No Berm - with 2oo-foot Channel" floodplain condition, approximately 113 of the 308 <br />acres of the Flatiron Property would be inundated during the 100-year flood. <br />Approximately ten (10) acres of the property inundated by the floodwaters under <br />Condition 1 could be removed from the floodplain by widening the interceptor channel at <br />the point of entrance into the property to accommodate the flood flows entering the site <br />at this location. The HEC-2 hydraulic model for Condition 1 is found in the Technical <br />Appendix of this report. <br /> <br />-15- <br />